In high pressure gradient liquid chromatography, the contribution of two or more solvents to the mobile phase changes over time. Generally, pumping systems for high pressure gradient liquid chromatography utilize parallel pumps to deliver multiple fluids in defined proportions to achieve a specified final fluid composition. Typically, each pump in the system is a combination of individual pump heads that are periodically refilled to maintain a constant fluid flow. The refilling process can cause disturbances or ripple in the flow and pressure of the delivered liquid due to a variety of factors, such as solvent compressibility and hydraulic inertia. If the refilling of a pump occurs during the pressure and flow disturbances resulting from the refilling of another pump, the solvent composition of the liquid delivered by the pumping system may not accurately match the desired solvent composition.